Rapid method for the determination of eight chlorophenoxy acid residues in environmental water samples using off-line solid-phase extraction and on-line selective precolumn switching

✍ Scribed by J.V. Sancho-Llopis; F. Hernández-Hernández; E.A. Hogendoorn; P. van Zoonen

• Publisher: Elsevier Science
• Year: 1993
• Tongue: English
• Weight: 544 KB
• Volume: 283
• Category: Article
• ISSN: 0003-2670
• DOI: 10.1016/0003-2670(93)85234-b

✦ Synopsis

Gctadecyl (C,,) bonded porous silica sorbent cartridges and Empore membrane extraction discs were evaluated for the solid-phase extraction (SPE) of organochlorine (lindane, dicofol, chlorfenson and tetradifon) and organophosphorus pesticides (dimethoate, fenitrothion and methidathion) from ground water. The SOO-mg Cts cartridges quantitatively adsorbed these pesticides, including the most polar (dimethoate), with recoveries ranging from 68 to 113% for a ground water sample spiked at the 0.1 pg I-' level. SPE with 500-mg C,, Empore discs also quantitatively adsorbed the pesticides with recoveries between 73 and 115% for the 0.1 pg I-' level, but only after eluting with 15 ml of ethyl acetate compared with 4 ml using cartridges and a longer analysis time per sample. After elution with ethyl acetate, the extract was concentrated to an appropriate volume, between 100 and 500 ~1, under a gentle stream of nitrogen. Detection limits were lower than 0.1 pg l-', which is currently the mazimum level allowed by the EEC for pesticide residues in drinking water. Determination was effected by capillary gas chromatography using electron-capture and nitrogen-phosphorus detectors.